oil cans , milk boxes ect

found this stuff in the garage most of the cans are still full and unopened i do however want to know can they be shipped with the stuff still in them or how do i empty them with out messing up there value?
the milk tins are insulated and from a dairy that has been closed down here for years the boxes were set on the front porch for the milk man to fill but i may be wrong any info on this kind of thing would be nice